Pipes or ductwork in dwellings, commercial buildings and industrial plants are used for heating or air conditioning purposes, and therefore carry fluids, such as heated or cooled air or steam. In industrial applications, pipes or ductwork also may carry chemicals or petroleum products or the like. The ductwork typically is formed of aluminum or steel, while the pipes may be formed of any suitable material, such as copper, steel, aluminum, plastic, rubber or other like materials.
Such pipes or ductwork and associated heating or air conditioning units typically are covered with an exterior layer of insulation. The insulation used to cover such pipes or ductwork and associated heating and air conditioning units often includes fiberglass, mineral wool, foamed cellular glass or a rigid foam, covered by a jacket. Materials which may be used in the insulation jacket include a layer or layers of foil, a layer or layers of paper, such as a kraft paper, a scrim and a layer of polyester. Ductboard is often used to cover ductwork.
When such pipes or ductwork are in a location exposed to weather elements, or when they are in other environments where the exterior insulation surface is subject to degradation by moisture or the like, it is common to cover the insulation with a facing. This is particularly true for insulation having an exterior layer of paper or for ductboard, whether or not the exposed outer surface is a metalized layer or a paper layer, to protect the insulation from moisture, sun, wind and other weather elements. One of the most commonly used facings is sheet metal, such as galvanized steel or aluminum, for example 0.5 to 1.0 millimeter thickness sheets of aluminum. Typically, flat metal sheets are prefabricated for a particular application at a workshop remote from the application site. These flat metal sheets are formed into three-dimensional pieces that are shaped and sized to conform to the pipe, duct or other conduit that is to be covered. These pre-formed sheets are then mounted over the insulation at the worksite and are attached with metal bands or the like. Such sheet metal facing is particularly used on pipes, columns and equipment in chemical and petro-chemical plants. However, sheet metal facing has certain drawbacks. In the first place, the prefabrication of these metal sheets at the factory into a desired shape and size is very time-consuming and thus expensive. The subsequent application of these products to the insulation covered conduits is also a time-consuming process. The metal facing also can be very heavy and therefore difficult to handle and manipulate at the jobsite. Both prefabrication and application require a specially skilled labor force who must be trained. In addition, the resulting sheet metal facing has a large number of joints which often are not completely sealed and which permit water to pass therethrough and thereby to wet the insulation. This wetting of the insulation is undesirable, and can result in corrosion of the underlying equipment and conduits. Any repair work can be quite costly and time-consuming.
Another known solution includes covering the insulation with butyl rubber. However, this solution also has drawbacks including the fact that the butyl rubber does not perform well and has a poor appearance. A butyl rubber covering tends to delaminate at temperatures below 0° F. and above 120° F., and therefore should not be used in extreme weather environments where such exterior coverings are most desired and are often necessary. Butyl rubber is also very difficult to apply because it is messy to cut and form, and it is very heavy. Butyl rubber has also been known to cause delamination of the outer surface of the insulation from the fiberglass or the wool disposed in the interior of the insulation, because of its weight and because of its lack of strength at elevated temperatures. Butyl rubber also tends to creep, has poor fire and smoke ratings and therefore is not UL listed. Finally, solvents are required to activate butyl rubber at temperatures below 45° F.
It is also known to cover insulation with thin layers of aluminum foil using a butyl rubber adhesive. However, such coverings have little or no puncture resistance, and the butyl rubber adhesive layer has the same drawbacks noted above for butyl rubber facing, including a tendency to run or ooze at elevated temperatures.
Scrim and mastics are also used to cover insulation. However, the use of such materials is often very labor-intensive and requires a multiple step process. These products can only be applied during certain weather conditions, and it is very difficult to regulate the thickness of mastic to make it uniform. Consequently, such products have very limited applications and generate a poor appearance.
Another known product is bitumen felt and netting. This product is very labor-intensive to apply and is not recommended for exterior use. It also has a very poor fire rating and is unsightly. Its use, therefore, is very limited.
There exists a need for a facing material for covering insulation, particularly exterior insulation, that is relatively inexpensive, easy to apply, can be easily cut with scissors or a knife, is puncture-resistant and has the strength, rigidity and resistance to corrosion of conventional aluminum facing.